Method for hydroformylation, xanthene-bridged ligands and catalyst comprising a complex of said ligands

ABSTRACT

In a process for the hydroformylation of ethylenically unsaturated compounds, at least one complex of a metal of transition group VIII. with at least one phosphorus-, arsenic- or antimony-containing compound as ligand is used as hydroformylation catalyst, where the compound used as ligand in each case comprises two groups which comprise a P, As or Sb atom and at least two further hetero atoms and are bound to a xanthene-like molecular framework. New compounds of this type and catalysts which comprise at least one complex of a metal of transition group VIII. with at least one such compound as ligand are also provided.

The present invention relates to a process for the hydroformylation ofethylenically unsaturated compounds, in which at least one complex of ametal of transition group VIII with at least one phosphorus-, arsenic-or antimony-containing compound as ligand is used as hydroformylationcatalyst, where the compound used as ligand in each case comprises atleast two groups which comprise a P, As or Sb atom and at least twofurther hetero atoms and are bound to a xanthene-like molecularframework. The invention also provides new compounds of this type andcatalysts which comprise at least one complex of a metal of transitiongroup VIII with at least one such compound as ligand.

Hydroformylation or the oxo process is an important industrial processand is employed for preparing aldehydes from olefins, carbon monoxideand hydrogen. If desired, these aldehydes can be hydrogenated by meansof hydrogen in the same process step to give the corresponding oxoalcohols. The reaction itself is strongly exothermic and generallyproceeds under superatmospheric pressure and at elevated temperatures inthe presence of catalysts. Catalysts used are Co, Rh, Ir, Ru, Pd or Ptcompounds or complexes which may be modified with N- or P-containingligands to influence the activity and/or selectivity. Thehydroformylation reaction results in formation of mixtures of isomericaldehydes because of the possible CO addition on to each of the twocarbon atoms of a double bond. In addition, double bond isomerization,i.e. shifting of internal double bonds to a terminal position and viceversa, can also occur.

Owing to the substantially greater industrial importance of α-aldehydes,optimization of the hydroformylation catalysts to achieve a very highhydroformylation activity together with a very low tendency to formdouble bonds not in the α position is sought. In addition, there is aneed for hydroformylation catalysts which lead to good yields ofα-aldehydes and in particular n-aldehydes even when internal linearolefins are used as starting materials. Here, the catalyst must makepossible both the establishment of equilibrium between internal andterminal double bond isomers and the very selective hydroformylation ofthe terminal olefins.

The use of phosphorus-containing ligands for stabilizing and/oractivating the catalyst metal in rhodium-catalyzed low-pressurehydroformylation is known. Suitable phosphorus-containing ligands are,for example, phosphines, phosphinites, phosphonites, phosphites,phosphoramidites, phospholes and phosphabenzenes. The most widespreadligands at present are triarylphosphines such as triphenylphosphine andsulfonated triphenylphosphine, since these have sufficient stabilityunder the reaction conditions. However, a disadvantage of these ligandsis that, in general, only very high ligand excesses give satisfactoryyields, in particular of linear aldehydes.

In Angew. Chem. Int. Ed. 39, 1639 (2000), D. Selent et al. describe theisomerizing hydroformylation of internal olefins in the presence ofrhodium catalysts, with oxy-functionalized bisphenyl monophosphonitesbeing used as ligands. A disadvantage of these catalysts is their lown-selectivity. Thus, in the hydroformylation of isomeric n-octenes,n-nonanal is obtained in a yield of at most 47.9%.

WO-A-98/43935 describes the use of chelating ligands in catalysts forhydroformylation.

In Tetrahedron Letters, Volume 34, No. 13, pages 2107 ff. (1993), inTetrahedron Letters, Volume 36, No. 1, pages 75 ff. (1995) and in Chem.Ber. 124, page 1705 ff. (1991), Haenel et al. describe the synthesis ofbis(diphenylphosphino)chelates having anthracene, dibenzofuran,dibenzothiophene and xanthene skeletons. The use of these compounds ascatalysts is not described.

In J. Chem. Soc., Dalton Trans., 1998, pp. 2981-2988, W. Goertz et al.describe the use of chelating phosphines and phosphonites having athioxanthene skeleton for the nickel-catalyzed hydrocyanation ofstyrene. Use in hydroformylation is not described.

In Organometallics 1995, 14, pages 3081 to 3089, M. Kranenburg et al.describe chelating phosphines having a xanthene skeleton and their usefor regioselective rhodium-catalyzed hydroformylation. Chelatingphosphonites and phosphites are not described in this document. Adisadvantage of these chelating phosphines is that they are not suitablefor the isomerizing hydroformylation of internal olefins with high α- orn-selectivity.

In Organometallics 1999, 18, pages 4765 to 4777, van der Veen et al.describe the use of phosphacyclic diphosphines having a xantheneskeleton as ligands for rhodium-catalyzed hydroformylation. Adisadvantage of these catalysts is their very low activity which makestheir use in industrial processes uneconomical.

WO 95/30680 describes bidentate phosphine ligands in which thephosphorus atoms may be bound to a xanthene skeleton and the use ofthese ligands in catalysts for hydroformylation. A disadvantage of thesecatalysts is that they are not suitable for the isomerizinghydroformylation of internal olefins with good α- or n-selectivity.

EP-A-0982314 describes bidentate carbocyclic or heterocyclic phosphineligands and a process for preparing linear aldehydes by hydroformylationof internal olefins using such ligands. A disadvantage of these ligandsis their very low activity which makes use in industrial processesuneconomical.

DE-A-19827232 describes catalysts based on monodentate, bidentate orpolydentate phosphinite ligands in which the phosphorus atom and theoxygen atom of the phosphinite group are part of a 5- to 8-memberedheterocycle, and their use in hydroformylation and hydrocyanation. Thebidentate ligands may have a xanthene skeleton. A disadvantage of theseligands is that they are in need of improvement in terms of the α- orn-selectivity in the isomerizing hydroformylation of internal olefins.

None of the abovementioned documents describes the use of chelatingphosphonites and phosphites having a xanthene skeleton as ligands incatalysts for hydroformylation.

It is an object of the present invention to provide an improved processfor the hydroformylation of compounds containing at least oneethylenically unsaturated double bond. Here, a very high proportion ofα-aldehydes or α-alcohols should preferably be obtained in thehydroformylation of α-olefins. In particular, the process should besuitable for the hydroformylation of internal linear olefins with highregioselectivity in favor of terminal product aldehydes. A furtherobject of the invention is to provide new compounds and novel catalystscomprising at least one complex of a metal of transition group VIII withsuch a compound as ligand.

We have found that these objects are achieved by a hydroformylationprocess in which at least one complex of a metal of transition groupVIII with at least one phosphorus-, arsenic- and/or antimony-containingcompound as ligand is used as hydroformylation catalyst. This compoundcomprises two groups comprising a P, As and/or Sb atom, with the P, Asand Sb atoms being bound directly to at least two further hetero atomsand with each of the two groups being bound to a different phenyl ringof a xanthene skeleton. The group is bound directly to the phenyl ringvia the phosphorus, arsenic or antimony atom or via a hetero atom boundthereto.

The present invention accordingly provides a process for thehydroformylation of compounds containing at least one ethylenicallyunsaturated double bond by reaction with carbon monoxide and hydrogen inthe presence of a hydroformylation catalyst comprising at least onecomplex of a metal of transition group VIII with at least one ligandselected from among compounds of the general formula I

where

-   A¹ and A² are each, independently of one another, O, S,    SiR^(a)R^(b), NR^(c) or CR⁵R⁶, where    -   R^(a), R^(b), R^(c), R⁵ and R⁶ are each, independently of one        another, hydrogen, alkyl, cycloalkyl, heterocycloalkyl, aryl or        hetaryl,-   Y¹ and Y² are each, independently of one another, radicals    containing at least one phosphorus, arsenic or antimony atom, where    in each case at least two substituted or unsubstituted hetero atoms    selected from among O, S and NR^(c), where R^(c) is hydrogen, alkyl,    cycloalkyl or aryl, are directly bound to the phosphorus, arsenic or    antimony atom, and-   R¹, R², R³ and R⁴ are each, independently of one another, hydrogen,    alkyl, cycloalkyl, heterocycloalkyl, aryl, hetaryl, COOR^(d),    COO⁻M⁺, SO₃R^(d), SO⁻ ₃M⁺, NE¹E², NE¹E²E³⁺X⁻, alkylene-NE¹E²E³⁺X⁻,    OR^(d), SR^(d), (CHR^(e)CH₂O)_(x)R^(d), (CH₂N(E¹))_(x)R^(d),    (CH₂CH₂N(E¹))_(x)R^(d), halogen, trifluoromethyl, nitro, acyl or    cyano,-    where    -   R^(d), E¹, E² and E³ are identical or different radicals        selected from among hydrogen, alkyl, cycloalkyl and aryl,    -   R^(e) is hydrogen, methyl or ethyl,    -   M⁺is a cation,    -   X⁻ is an anion, and    -   x is an integer from 1 to 120, or-   R¹ and/or R³ together with two adjacent carbon atoms of the benzene    ring to which they are bound form a fused ring system having 1, 2 or    3 further rings.

For the purposes of the present invention, the expression ‘alkyl’encompasses straight-chain and branched alkyl groups. They arepreferably straight-chain or branched C₁-C₁₂-alkyl groups, morepreferably C₁-C₈-alkyl groups and particularly preferably C₁-C₄-alkylgroups. Examples of alkyl groups are, in particular, methyl, ethyl,propyl, isopropyl, n-butyl, 2-butyl, sec-butyl, tert-butyl, n-pentyl,2-pentyl, 2-methylbutyl, 3-methylbutyl, 1,2-dimethylpropyl,1,1-dimethylpropyl, 2,2-dimethylpropyl, 1-ethylpropyl, n-hexyl, 2-hexyl,2-methylpentyl, 3-methylpentyl, 4-methylpentyl, 1,2-dimethylbutyl,1,3-dimethylbutyl, 2,3-dimethylbutyl, 1,1-dimethylbutyl,2,2-dimethylbutyl, 3,3-dimethylbutyl, 1,1,2-trimethylpropyl,1,2,2-trimethylpropyl, 1-ethylbutyl, 2-ethylbutyl,1-ethyl-2-methylpropyl, n-heptyl, 2-heptyl, 3-heptyl, 2-ethylpentyl,1-propylbutyl, octyl.

Substituted alkyl radicals preferably have 1, 2, 3, 4 or 5, inparticular 1, 2 or 3, substituents selected from among cycloalkyl, aryl,hetaryl, halogen, NE¹E², NE¹E²E³⁺, carboxyl, carboxylate, —SO₃H andsulfonate.

A cycloalkyl group is preferably a C₅-C₇-cycloalkyl group such ascyclopentyl, cyclohexyl and cycloheptyl.

If the cycloalkyl group is substituted, it preferably has 1, 2, 3, 4 or5, in particular 1, 2 or 3, substituents selected from among alkyl,alkoxy and halogen.

Aryl is preferably phenyl, tolyl, xylyl, mesityl, naphthyl, anthracenyl,phenanthrenyl, naphthacenyl, in particular phenyl or naphthyl.

Substituted aryl radicals preferably have 1, 2, 3, 4 or 5, in particular1, 2 or 3, substituents selected from among alkyl, alkoxy, carboxyl,carboxylate, trifluoromethyl, —SO₃H, sulfonate, NE¹E², alkylene-NE¹E²,nitro, cyano and halogen.

Hetaryl is preferably pyridyl, quinolinyl, acridinyl, pyridazinyl,pyrimidinyl or pyrazinyl.

Substituted hetaryl radicals preferably have 1, 2 or 3 substituentsselected from among alkyl, alkoxy, carboxyl, carboxylate, —SO₃H,sulfonate, NE¹E², alkylene-NE¹E², trifluoromethyl and halogen.

What has been said above in respect of alkyl, cycloalkyl and arylradicals applies analogously to alkoxy, cycloalkyloxy and aryloxyradicals.

The radicals NE¹E² and NE⁴E⁵ are preferably N,N-dimethylamino,N,N-diethylamino, N,N-dipropylamino, N,N-diisopropylamino,N,N-di-n-butylamino, N,N-di-t-butylamino, N,N-dicyclohexylamino orN,N-diphenylamino.

Halogen is fluorine, chlorine, bromine or iodine, preferably fluorine,chlorine or bromine.

For the purposes of the present invention, carboxylate and sulfonate arepreferably each a derivative of a carboxylic acid function or a sulfonicacid function, in particular a metal carboxylate or sulfonate, acarboxylic ester or sulfonic ester function or a carboxamide orsulfonamide function. These include, for example, esters ofC₁-C₄-alkanoles such as methanol, ethanol, n-propanol, isopropanol,n-butanol, sec-butanol and tert-butanol.

Y¹ and Y² are preferably each a radical containing a phosphorus atom andin particular a radical of the formula P(OR⁷)(OR⁸), OP(OR⁷)R⁸ orOP(OR⁷)(OR⁸), where

-   R⁷ and R⁸ are each, independently of one another, alkyl, cycloalkyl,    heterocycloalkyl, aryl or hetaryl which may bear one, two or three    substituents selected from among alkyl, cycloalkyl,    heterocycloalkyl, aryl, hetaryl, COOR^(f), COO⁻M⁺, SO₃R^(f), SO⁻    ₃M⁺, NE⁴E⁵, alkylene-NE⁴E⁵, NE⁴E⁵E⁶⁺X⁻, alkylene-NE⁴E⁵E⁶⁺X⁻, OR^(f),    SR^(f), (CHR^(g)CH₂O)_(y)R^(f), (CH₂N(E⁴))_(y)R^(f),    (CH₂CH₂N(E⁴))_(y)R^(f), halogen, trifluoromethyl, nitro, acyl and    cyano,-    where    -   R^(f), E⁴, E⁵ and E⁶ are identical or different radicals        selected from among hydrogen, alkyl, cycloalkyl or aryl,    -   R^(g) is hydrogen, methyl or ethyl,    -   M⁺is a cation,    -   X⁻ is an anion, and    -   y is an integer from 1 to 120, or-   R⁷ and R⁸ together with the phosphorus atom and the oxygen atom(s)    to which they are bound form a 5- to 8-membered heterocycle to which    one, two or three cycloalkyl, heterocycloalkyl, aryl or hetaryl    groups may additionally be fused, where the heterocycle and, if    present, the fused-on groups may each bear, independently of one    another, one, two, three or four substituents selected from among    alkyl, cycloalkyl, heterocycloalkyl, aryl, hetaryl, COOR^(f),    COO⁻M⁺, SO₃R^(f), SO⁻ ₃M⁺, NE⁴E⁵, alkylene-NE⁴E⁵, NE⁴E⁵E⁶⁺X⁻,    alkylene-NE⁴E⁵E⁶⁺X⁻, OR^(f), SR^(f), (CHR^(g)CH₂O)_(y)R^(f),    (CH₂N(E⁴))_(y)R^(f), (CH₂CH₂N(E⁴))_(y)R^(f), halogen,    trifluoromethyl, nitro, acyl and cyano, where R^(f), R^(g), E⁴, E⁵,    E⁶, M⁺, X⁻ and y are as defined above.

In a preferred embodiment, one of the radicals Y¹ or Y² or both radicalsY¹ and Y² in the formula I are selected from among radicals of theformulae P(OR⁷)(OR⁸), OP(OR⁷)R⁸ and OP(OR⁷)(OR⁸) in which R⁷ and R⁸together with the phosphorus atom and the oxygen atom(s) to which theyare bound form a 5- to 8-membered heterocycle to which one, two or threecycloalkyl, heterocycloalkyl, aryl and/or hetaryl groups mayadditionally be fused, where the heterocycle and/or the fused-on groupsmay each, independently of one another, bear one, two, three or foursubstituents selected from among alkyl, alkoxy, halogen, nitro, cyano,carboxyl, SO₃H, sulfonate, NE⁴E⁵, alkylene-NE⁴E⁵ and carboxylate.

The radicals Y¹ and Y² are preferably selected from among phosphoniteand/or phosphite radicals of the formula II

where

-   r, s and t are each, independently of one another, 0 or 1 and the    sum of r, s and t is at least 2,-   D together with the phosphorus atom and the oxygen atom(s) to which    it is bound form a 5- to 8-membered heterocycle to which one, two or    three cycloalkyl, heterocycloalkyl, aryl and/or hetaryl groups may    be fused, where the fused-on groups may each bear, independently of    one another, one, two, three or four substituents selected from    among alkyl, alkoxy, halogen, SO₃H, sulfonate, NE⁴E⁵,    alkylene-NE⁴E⁵, nitro, cyano, carboxyl and carboxylate, and/or D may    have one, two or three substituents selected from among alkyl,    alkoxy, substituted or unsubstituted cycloalkyl and substituted or    unsubstituted aryl, and/or D may be interrupted by 1, 2 or 3    substituted or unsubstituted hetero atoms.

The radical D is preferably a C₂-C₆-alkylene bridge to which 1 or 2 arylgroups are fused and/or may have a substituent selected from amongalkyl, substituted or unsubstituted cycloalkyl and substituted orunsubstituted aryl, and/or may be interrupted by a substituted orunsubstituted hetero atom.

The fused-on arylene of the radical D is preferably benzene ornaphthalene. Fused-on benzene rings are preferably unsubstituted or have1, 2 or 3, in particular 1 or 2, substituents selected from among alkyl,alkoxy, halogen, SO₃H, sulfonate, NE⁴E⁵, alkylene-NE⁴E⁵,trifluoromethyl, nitro, carboxyl, alkoxycarbonyl, acyl and cyano.Fused-on naphthalenes are preferably unsubstituted or have 1, 2 or 3, inparticular 1 or 2, of the substituents mentioned above for the fused-onbenzene rings in the ring which is not fused on and/or in the fused-onring. An alkyl substituent on the fused-on aryls is preferablyC₁-C₄-alkyl and in particular methyl, isopropyl or tert-butyl. Alkoxy ispreferably C₁-C₄-alkoxy and in particular methoxy. Alkoxycarbonyl ispreferably C₁-C₄-alkoxycarbonyl. Halogen is particularly preferablyfluorine or chlorine.

If the C₂-C₆-alkylene bridge of the radical D is interrupted by 1, 2 or3 substituted or unsubstituted hetero atoms, these are preferablyselected from among O, S and NR^(h), where R^(h) is alkyl, cycloalkyl oraryl. The C₂-C₆-alkylene bridge of the radical D is preferablyinterrupted by one substituted or unsubstituted hetero atom.

If the C₂-C₆-alkylene bridge of the radical D is substituted, itpreferably has 1, 2 or 3, in particular 1, substituents selected fromamong alkyl, cycloalkyl and aryl, where the aryl substituent may bear 1,2 or 3 of the substituents mentioned for aryl. The alkylene bridge Dpreferably has one substituent selected from among methyl, ethyl,isopropyl, phenyl, p-(C₁-C₄-alkyl)phenyl, preferably p-methylphenyl,p-(C₁-C₄-alkoxy)phenyl, preferably p-methoxyphenyl, p-halophenyl,preferably p-chlorophenyl, and p-trifluoromethylphenyl.

The radical D is preferably a C₃-C₆-alkylene bridge which is fusedand/or substituted and/or interrupted by substituted or unsubstitutedhetero atoms as described above. In particular, the radical D is aC₃-C₆-alkylene bridge on to which one or two phenyl and/or naphthylgroups are fused, where the phenyl or naphthyl groups may bear 1, 2 or3, in particular 1 or 2, of the abovementioned substituents.

Preference is given to the radical D (i.e. R⁷ and R⁸ together) togetherwith the phosphorus atom and the oxygen atom(s) to which it is boundforming a 5- to 8-membered heterocycle, with the radical D (R⁷ and R⁸together) being a radical selected from among the radicals of theformulae II.1 to II.5,

where

-   z is O, S or NR^(i), where    -   R^(i) is alkyl, cycloalkyl or aryl,-   or Z is a C₁-C₃-alkylene bridge which may have a double bond and/or    an alkyl, cycloalkyl or aryl substituent, where the aryl substituent    may bear one, two or three of the substituents mentioned for aryl,-   or Z is a C₂-C₃-alkylene bridge which is interrupted by O, S or    NR^(i),-   R⁹, R¹⁰, R¹¹, R¹², R¹³, R¹⁴, R¹⁵ and R¹⁶ are each, independently of    one another, hydrogen, alkyl, cycloalkyl, aryl, alkoxy, halogen,    SO₃H, sulfonate, NE⁴E⁵, alkylene-NE⁴E⁵, trifluoromethyl, nitro,    alkoxycarbonyl, carboxyl or cyano.

D is preferably a radical of the formula II.1 in which R⁹ and R¹⁰ areeach hydrogen.

D is preferably a radical of the formula II.2a

where

-   R⁹ is hydrogen, C₁-C₄-alkyl, C₁-C₄-alkoxy, SO₃H, sulfonate, NE⁴E⁵,    alkylene-NE⁴E⁵, preferably hydrogen, C₁-C₄-alkyl or C₁-C₄-alkoxy, in    particular methyl, methoxy, isopropyl or tert-butyl,-   R¹⁰ is hydrogen, C₁-C₄-alkyl, preferably methyl, isopropyl or    tert-butyl, C₁-C₄-alkoxy, preferably methoxy, fluorine, chlorine or    trifluoromethyl. R¹⁰ may also be SO₃H, sulfonate, NE⁴E⁵ or    alkylene-NE⁴E⁵.

D is prefeably a radical of the formula II.3a

where

-   R⁹ and R¹⁰ are as defined for the formula II.2a,-   R¹ is hydrogen, C₁-C₄-alkyl, preferably methyl or ethyl, phenyl,    p-(C₁-C₄-alkoxy)phenyl, preferably p-methoxyphenyl, p-fluorophenyl,    p-chlorophenyl or p-(trifluoromethyl)phenyl.

D is preferably a radical of the formula II.4 in which R⁹, R¹⁰, R¹¹,R¹², R¹³, R¹⁴, R¹⁵ and R¹⁶ are each hydrogen.

D is preferably a radical of the formula II.4 in which R⁹, R¹⁰, R¹¹,R¹², R¹⁴ and R¹⁶ are each hydrogen and the radicals R¹³ and R¹⁵ areeach, independently of one another, alkoxycarbonyl, preferablymethoxycarbonyl, ethoxycarbonyl, n-propyloxycarbonyl orisopropyloxycarbonyl. In particular, the radicals R¹³ and R¹⁵ arelocated in the ortho position relative to the phosphorus atom or oxygenatom.

D is preferably a radical of the formula II.5 in which R⁹, R¹⁰, R¹¹,R¹², R¹³, R¹⁴, R¹⁵ and R¹⁶ are each hydrogen and Z is CR^(l), where R¹is as defined above.

D is preferably a radical of the formula II.5 in which R⁹, R¹⁰, R¹¹,R¹², R¹⁴ and R¹⁶ are each hydrogen, Z is CR^(h) and the radicals R¹³ andR¹⁵ are each, independently of one another, alkoxycarbonyl, preferablymethoxycarbonyl, ethoxycarbonyl, n-propyloxycarbonyl orisopropyloxycarbonyl. In particular, the radicals R¹³ and R¹⁵ arelocated in the ortho position relative to the phosphorus atom or oxygenatom.

In a further, preferred embodiment, one of the radicals Y¹ or Y² or bothradicals Y¹ and Y² in the formula I are selected from among radicals ofthe formulae P(OR⁷)(OR⁸), OP(OR⁷)R⁸ and OP(OR⁷)(OR⁸) in which R⁷ and R⁸do not together form a heterocycle.

The radicals R⁷ and R⁸ are preferably each, independently of oneanother, alkyl, aryl or hetaryl which may bear one, two or threesubstituents selected from among alkyl (only for aryl or hetaryl),cycloalkyl, aryl, alkoxy, cycloalkoxy, aryloxy, halogen,trifluoromethyl, nitro, cyano, carboxyl, carboxylate, acyl, —SO₃H,sulfonate, NE⁴E⁵ and alkylene-NE⁴E⁵, where E⁴ and E⁵ are identical ordifferent and are selected from among alkyl, cycloalkyl and aryl.

The radicals R⁷ and R⁸ are preferably selected independently from amongthe radicals of the formulae II.6 and II.7

where

-   R⁹ and R¹⁰ are each, independently of one another, hydrogen,    C₁-C₄-alkyl, COOR^(f), COO⁻M⁺, SO₃R^(d), SO₃ ⁻M⁺, NE⁴E⁵,    alkylene-NE⁴E⁵, NE⁴E⁵E⁶⁺X⁻, alkylene-NE⁴E⁵E⁶⁺X⁻, C₁-C₄-alkoxy,    halogen or trifluoromethyl, where R^(f), E⁴, E⁵ and E⁶ may be    identical or different and are each hydrogen, alkyl, cycloalkyl or    aryl, M⁺ is a cation and X⁻ is an anion.

In the formulae II.6 and II.7, the radicals R⁹ and R¹⁰ are preferablyeach, independently of one another, hydrogen, C₁-C₄-alkyl orC₁-C₄-alkoxy, in particular methyl, methoxy, isopropyl or tert-butyl.

A¹ and A² are preferably each, independently of one another, O, S andCR⁵R⁶, where R⁵ and R⁶ are each, independently of one another, hydrogen,alkyl, cycloalkyl, aryl or hetaryl. In particular, R⁵ and R⁶ are each,independently of one another, hydrogen or C₁-C₄-alkyl such as methyl,ethyl, n-propyl, n-butyl or tert-butyl. In particular, R⁵ and R⁶ areboth methyl.

Preference is given to one of the radicals A¹ or A² being O or S and theother being CR⁵R⁶. More preferably, the radicals A¹ and A² are selectedfrom among O and S.

The radicals R¹, R², R³ and R⁴ are preferably selected from amonghydrogen, alkyl, cycloalkyl, aryl and hetaryl. Preference is given to R¹and R³ being hydrogen and R² and R⁴ being C₁-C₄-alkyl such as methyl,ethyl, n-propyl, n-butyl or tert-butyl.

At least one of the radicals R¹, R², R³ and/or R⁴ is preferably a polar(hydrophilic) group, which then generally results in water-solublecatalysts. The polar groups are preferably selected from among COOR^(d),COO⁻M⁺, SO₃R^(d), SO⁻ ₃M⁺, NE¹E², alkylene-NE¹E², NE¹E²E³⁺X⁻,alkylene-NE¹E²E³⁺X⁻, OR^(d), SR^(d), (CHR^(e)CH₂O)_(x)R^(d) or(CH₂CH₂N(E¹))_(x)R^(d), where R^(d), E¹, E², E³, R^(d), R^(e), M⁺, X⁻and x are as defined above.

R¹, R², R³ and R⁴ are particularly preferably each hydrogen.

If R¹ and/or R³ form a fused-on ring system, the fused-on groups arepreferably benzene or naphthalene groups. Fused-on benzene rings arepreferably unsubstituted or have 1, 2 or 3, in particular 1 or 2,substituents selected from among alkyl, alkoxy, halogen, SO₃H,sulfonate, NE⁴E⁵, alkylene-NE⁴E⁵, trifluoromethyl, nitro, carboxyl,alkoxycarbonyl, acyl and cyano. Fused-on naphthalenes are preferablyunsubstituted or have 1, 2, or 3, in particular 1 or 2, of thesubstituents mentioned above for the fused-on benzene rings in the ringwhich is not fused on and/or in the fused-on ring.

M⁺ is preferably an alkali metal cation, e.g. Li⁺, Na⁺or K⁺, NH₄ ⁺or aquarternary ammonium compound as is obtainable by protonation orquaternization of amines.

X⁻ is preferably halide, particularly preferably Cl⁻ or Br⁻.

In a preferred embodiment of the process of the present invention, useis made of a hydroformylation catalyst in which the compound of theformula I is selected from among the compounds of the formulae I.1 toI.6

where

-   A¹ is O, S or CR⁵R⁶, where R⁵ and R⁶ are each, independently of one    another, hydrogen or C₁-C₄-alkyl, in particular methyl or    tert-butyl,-   R¹⁷, R¹⁸, R¹⁹, R²⁰, R²¹, R²², R²³ and R²⁴ are each, independently of    one another,-    hydrogen, alkyl, preferably C₁-C₄-alkyl, in particular methyl or    tert-butyl, cycloalkyl, heterocycloalkyl, aryl, hetaryl, COOR^(d),    COO⁻M⁺, SO₃R^(f), SO⁻ ₃M⁺, NE⁴E⁵, alkylene-NE⁴E⁵, NE⁴E⁵E⁶⁺X⁻,    alkylene-NE⁴E⁵E⁶⁺X⁻, OR^(f), preferably C₁-C₄-alkoxy, in particular    methoxy, SR^(f), (CHR^(g)CH₂O)_(y)R^(f), (CH₂N(E⁴))_(y)R^(f),    (CH₂CH₂N(E⁴))_(y)R^(f), halogen, trifluoromethyl, nitro, acyl and    cyano,-    where    -   R^(f), E⁴, E⁵ and E⁶ are identical or different radicals        selected from among hydrogen, alkyl, preferably C₁-C₄-alkyl, in        particular methyl or tert-butyl, alkoxy, preferably methoxy,        cycloalkyl and aryl,    -   R^(g) is hydrogen, methyl or ethyl,    -   M⁺is a cation,    -   X⁻ is an anion, and    -   y is an integer from 1 to 120.

The invention further provides compounds of the formula I

where

-   A¹ and A² are each, independently of one another, O, S,    SiR^(a)R^(b), NR^(c) or CR⁵R⁶, with the exception of A¹=S and A²=O,    where    -   R^(a), R^(b), R^(c), R⁵ and R⁶ are each, independently of one        another, hydrogen, alkyl, cycloalkyl, heterocycloalkyl, aryl or        hetaryl,-   Y¹ and Y² are each, independently of one another, radicals    containing at least one phosphorus, arsenic or antimony atom, where    in each case at least two substituted or unsubstituted heteroatoms    selected from among O, S and NR^(c), where R^(c) is hydrogen, alkyl,    cycloalkyl or aryl, are directly bound to the phosphorus, arsenic or    antimony atom, and-   R¹, R², R³ and R⁴ are each, independently of one another, hydrogen,    alkyl, cycloalkyl, heterocycloalkyl, aryl, hetaryl, COOR^(d),    COO⁻M⁺, SO₃R^(d), SO⁻ ₃M⁺, NE¹E², NE¹E²E³⁺X⁻, alkylene-NE¹E²E³⁺X⁻,    OR^(d), SR^(d), (CHR^(e)CH₂O)_(x)R^(d), (CH₂N(E¹))_(x)R^(d),    (CH₂CH₂N(E¹))_(x)R^(d), halogen, trifluoromethyl, nitro, acyl or    cyano,-    where    -   R^(d), E¹, E² and E³ are identical or different radicals        selected from among hydrogen, alkyl, cycloalkyl and aryl,    -   R^(e) is hydrogen, methyl or ethyl,    -   M⁺ is a cation,    -   X⁻ is an anion, and    -   x is an integer from 1 to 120, or-   R¹ and/or R³ together with two adjacent carbon atoms of the benzene    ring to which they are bound form a fused ring system having 1, 2 or    3 further rings.

As regards preferred embodiments of the compounds of the formula I,reference may be made to what has been said above in respect of theligands of the formula I used in the hydroformylation process of thepresent invention.

The invention further provides a catalyst comprising at least onecomplex of a metal of transition group VIII with at least one novelcompound of the formula I as defined above.

The catalysts of the present invention and those used according to thepresent invention may comprise one or more of the compounds of theformula I as ligands. In addition to the above-described ligands of theformula I, they may further comprise at least one additional ligandselected from among halides, amines, carboxylates, acetylacetonate,arylsulfonates and alkylsulfonates, hydride, CO, olefins, dienes,cycloolefins, nitriles, N-containing heterocycles, aromatics andheteroaromatics, ethers, PF₃, phospholes, phosphabenzenes andmonodentate, bidentate and polydentate phosphine, phosphinite,phosphonite, phosphoramidite and phosphite ligands.

The metal of transition group VIII is preferably cobalt, ruthenium,rhodium, palladium, platinum, osmium or iridium, in particular cobalt,rhodium, ruthenium or iridium.

The preparation of the compounds of the formula I used according to thepresent invention and the novel compounds of the formula I can becarried out, for example, starting from a compound of the formula I.a

where

-   Y^(a) and Y^(b) are each, independently of one another, a radical Y¹    or Y² as defined above, or Y^(a) and Y^(b) are each, independently    of one another, halogen, OH, OC(O)CF₃ or SO₃Me where Me=hydrogen,    Li, Na or K, and Y^(a) and/or Y^(b) may also be hydrogen if at least    one of the radicals R² and/or R⁴ is hydrogen, an alkoxy group or an    alkoxycarbonyl group located in the ortho position relative to Y^(a)    and/or Y^(b), and-   A¹, A², R¹, R², R³ and R⁴ are as defined above.

The functionalization of the radicals Y^(a) and Y^(b) to form theradicals Y¹ and Y² can be carried out in a manner analogous to knownmethods. For example, compounds of the formula I.a in which Y^(a) andY^(b) are halogen, preferably chlorine, can firstly be lithiated and theintermediate formed can be reacted with a compound which bears a halogenatom, preferably a chlorine atom, on the phosphorus atom, for example acompound of the formula Cl-P(OR⁷)₂, Cl-P(OR⁷)(OR⁸) or Cl-P(OR⁷)₂. Thenovel compounds I in which Y¹ and Y² are each a radical of the formulaII in which t=0 are prepared by, for example, reaction of I.a withcompounds of the formula II.a according to the following scheme,

where r, s and D are as defined above for the compounds of the formulaII.

In place of compounds of the formula I.a in which Y^(a)=Y^(b)=halogen,it is also possible to lithiate compounds I.a in whichY^(a)=Y^(b)=hydrogen and in which hydrogen, an alkoxy group or analkoxycarbonyl group is present in each of the ortho positions relativeto Y^(a) and Y^(b). Such reactions are described in the literature underthe name “Ortho-Lithiation” (see, for example, D. W. Slocum, J. Org.Chem., 1976, 41, 3652-3654; J. M. Mallan, R. L. Bebb, Chem. Rev., 1969,693 ff; V. Snieckus, Chem. Rev., 1980, 6, 879-933). The organolithiumcompounds obtained in this way can then be reacted with the phosphorushalide compounds in the manner indicated above to form the targetcompounds I.

The arsenic compounds I and the antimony compounds I can be prepared inan analogous way.

In general, the catalysts or catalyst precursors used in each case areconverted under hydroformylation conditions into catalytically activespecies of the formula H_(x)M_(y)(CO)_(z)L_(q), where M is a metal oftransition group VIII, L is a phosphorus-, arsenic- orantimony-containing compound of the formula I and q, x, y, z areintegers which depend on the valence and type of the metal and also thenumber of coordination positions occupied by the ligand L. z and q arepreferably, independently of one another, at least 1, e.g. 1, 2 or 3.The sum of z and q is preferably from 2 to 5. If desired, the complexesmay further comprise at least one of the above-described additionalligands.

In a preferred embodiment, the hydroformylation catalysts are preparedin situ in the reactor used for the hydroformylation reaction. However,if desired, the catalysts used according to the present invention canalso be prepared separately and isolated by customary methods. Toprepare the catalysts used according to the present invention in situ,it is possible, for example, to react at least one compound of theformula I, a compound or a complex of a metal of transition group VIII,if desired at least one further additional ligand and, if desired, anactivating agent in an inert solvent under the hydroformylationconditions.

Suitable rhodium compounds or complexes are, for example, rhodium(II)and rhodium(III) salts, e.g. rhodium(III) chloride, rhodium(III)nitrate, rhodium(III) sulfate, potassium rhodium sulfate, rhodium(II)and rhodium(III) carboxylates, rhodium(II) and rhodium(III) acetate,rhodium(III) oxide, salts of rhodic(III) acid, trisammoniumhexachlororhodate(III), etc. Also suitable are rhodium complexes such asdicarbonylrhodium acetylacetonate, acetylacetonatobisethylenerhodium(I),etc. Preference is given to using dicarbonylrhodium acetylacetonate orrhodium acetate.

Ruthenium salts or compounds are likewise suitable. Suitable rutheniumsalts are, for example, ruthenium(III) chloride, ruthenium(IV),ruthenium(VI) or ruthenium(VIII) oxide, alkali metal salts of rutheniumoxo acids such as K₂RuO₄ or KRuO₄ or complexes such as RuHCl(CO)(PPh₃)₃.It is also possible to use the carbonyls of ruthenium, e.g.dodecacarbonyltriruthenium or octadecacarbonylhexaruthenium, or mixedforms in which Co has been partially replaced by ligands of the formulaPR₃, e.g. Ru(CO)₃(PPh₃)₂, in the process of the present invention.

Suitable cobalt compounds are, for example cobalt(II) chloride,cobalt(II) sulfate, cobalt(II) carbonate, cobalt(II) nitrate, theiramine or hydrate complexes, cobalt carboxylates such as cobalt acetate,cobalt ethylhexanoate, cobalt naphthanoate, and also the caprolactamatecomplex of cobalt. Here too, the carbonyl complexes of cobalt, e.g.octacarbonyldicobalt, dodecacarbonyltetracobalt andhexadecacarbonylhexacobalt, can be used.

The abovementioned and further suitable compounds of cobalt, rhodium,ruthenium and iridium are known in principle and are adequatelydescribed in the literature or they can be prepared by a person skilledin the art using methods analogous to those for known compounds.

Suitable activating agents are, for example, Brönsted acids, Lewisacids, e.g. BF₃, AlCl₃, ZnCl₂, and Lewis bases.

As solvents, preference is given to using the aldehydes which are formedin the hydroformylation of the respective olefins, and also theirhigher-boiling downstream reaction products, e.g. the products of thealdol condensation. Further suitable solvents are aromatics such astoluene and xylenes, hydrocarbons or mixtures of hydrocarbons, also fordilution of the abovementioned aldehydes and the downstream products ofthe aldehydes. Further solvents are esters of aliphatic carboxylic acidswith alkanoles, for example ethyl acetate or Texanol™, ethers such astert-butyl methyl ether and tetrahydrofuran. In the case of sufficientlyhydrophilic ligands, it is also possible to use alcohols such asmethanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol,ketones, such as acetone and methyl ethyl ketone etc.

“Ionic liquids” can also be used as solvents. These are liquid salts,for example N,N′-dialkylimidazolium salts such asN-butyl-N′-methylimidazolium salts, tetraalkylammonium salts such astetra-n-butylammonium salts, N-alkylpyridinium salts such asn-butylpyridinium salts, tetraalkylphosphonium salts such astrishexyl(tetradecyl)phosphonium salts, e.g. the tetrafluoroborates,acetates, tetrachloroaluminates, hexafluorophosphates, chlorides andtosylates.

Furthermore, the reactions can also be carried out in water or aqueoussolvent systems comprising water together with a water-miscible solvent,for example an alcohol such as methanol, ethanol, n-propanol,isopropanol, n-butanol, isobutanol, a ketone such as acetone or methylethyl ketone or another solvent. For this purpose, use is made ofligands of the formula I which have been modified with polar groups, forexample ionic groups such as SO₃Me, CO₂Me where Me=Na, K or NH₄, or suchas N(CH₃)₃ ⁺. The reactions then occur as a two-phase catalysis in whichthe catalyst is present in the aqueous phase and starting materials andproducts form the organic phase. The reaction in the “ionic liquids” canalso be carried out as a two-phase catalysis.

The molar ratio of phosphorus-containing ligand to metal of transitiongroup VIII is generally in a range from about 1:1 to 1000:1.

Suitable substrates for the hydroformylation process of the presentinvention are in principle all compounds which contain one or moreethylenically unsaturated double bonds. These include, for example,olefins such as α-olefins, internal straight-chain and internal branchedolefins. Suitable α-olefins are, for example, ethylene, propene,1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene,1-undecene, 1-dodecene, etc.

Preferred branched, internal olefins are C₄-C₂₀-olefins such as2-methyl-2-butene, 2-methyl-2-pentene, 3-methyl-2-pentene, branched,internal heptene mixtures, branched, internal octene mixtures, branched,internal nonene mixtures, branched, internal decene mixtures, branched,internal undecene mixtures, branched, internal dodecene mixtures, etc.

Further suitable olefins for the hydroformylation are C₅-C₈-cycloalkenessuch as cyclopentene, cyclohexene, cycloheptene, cyclooctene and theirderivatives, e.g. their C₁-C₂₀-alkyl derivatives having from 1 to 5alkyl substituents. Olefins suitable for hydroformylation also includevinyl aromatics such as styrene, α-methylstyrene, 4-isobutylstyrene,etc. Other suitable olefins for the hydroformylation areα,β-ethylenically unsaturated monocarboxylic and/or dicarboxylic acids,their esters, monoesters and amides, e.g. acrylic acid, methacrylicacid, maleic acid, fumaric acid, crotonic acid, itaconic acid, methyl3-penteneoate, methyl 4-penteneoate, methyl oleate, methyl acrylate,methyl methacrylate, unsaturated nitriles such as 3-pentenenitrile,4-pentenenitrile, acrylonitrile, vinyl ethers such as vinyl methylether, vinyl ethyl ether, vinyl propyl ether, etc., C₁-C₂₀-alkenols,-alkenediols and -alkadienoles, e.g. 2,7-octadien-1-ol. Further suitablesubstrates are dienes or polyenes containing isolated or conjugateddouble bonds. These include, for example, 1,3-butadiene, 1,4-pentadiene,1,5-hexadiene, 1,6-heptadiene, 1,7-octadiene, vinylcyclohexene,dicyclopentadiene, 1,5,9-cyclooctatriene and also homopolymers andcopolymers of butadiene.

The unsaturated compound used for the hydroformylation is preferablyselected from among internal linear olefins and olefin mixtures in whichat least one internal linear olefin is present. Preferred linear(straight-chain) internal olefins are C₄-C₂₀-olefins such as 2-butene,2-pentene, 2-hexene, 3-hexene, 2-heptene, 3-heptene, 2-octene, 3-octene,4-octene, etc., and mixtures thereof.

In the hydroformylation process of the present invention, preference isgiven to using an olefin mixture which is available on an industrialscale and comprises, in particular, at least one internal linear olefin.These include, for example, the Ziegler olefins obtained by controlledethene oligomerization in the presence of alkylaluminum catalysts. Theseare essentially unbranched olefins having a terminal double bond and aneven number of carbon atoms. Further examples are the olefins obtainedby ethene oligomerization in the presence of various catalyst systems,e.g. the predominantly linear α-olefins obtained in the presence ofalkylaluminum chloride/titanium tetrachloride catalysts and theα-olefins obtained by the Shell Higher Olefin Process (SHOP) in thepresence of nickel-phosphine complexes as catalysts. Further suitableindustrially available olefin mixtures are obtained in the paraffindehydrogenation of appropriate petroleum fractions, e.g. kerosene ordiesel oil fractions. To convert paraffins, predominantly n-paraffins,into olefins, essentially three processes are used:

-   -   thermal cracking (steam cracking),    -   catalytic dehydrogenation and    -   chemical dehydrogenation by chlorination and        dehydrochlorination.

Thermal cracking leads predominantly to α-olefins, while the othervariants produce olefin mixtures which generally also have relativelyhigh proportions of olefins containing an internal double bond. Furthersuitable olefin mixtures are the olefins obtained in metathesis ortelomerization reactions. They include, for example, the olefins fromthe Phillips triolefin process, a modified SHOP comprising ethyleneoligomerization, double bond isomerization and subsequent metathesis(ethenolysis).

Further suitable industrial olefin mixtures which can be used in thehydroformylation process of the present invention are selected fromamong dibutenes, tributenes, tetrabutenes, dipropenes, tripropenes,tetrapropenes, mixtures of butene isomers, in particular raffinate II,dihexenes, dimers and oligomers from the Dimersol® process of IFP, theOctol® process of Hüls, the Polygas process, etc.

Preference is given to a process in which the hydroformylation catalystis prepared in situ by reacting at least one compound of the formula I,a compound or a complex of a metal of transition group VIII and, ifdesired, an activating agent in an inert solvent under thehydroformylation conditions.

The hydroformylation reaction can be carried out continuously,semicontinuously or batchwise.

Suitable reactors for the continuous reaction are known to those skilledin the art and are described, for example, in Ullmanns Enzyklopädie dertechnischen Chemie, Vol. 1, 3rd Edition, 1951, p. 743 ff.

Suitable pressure-rated reactors are likewise known to those skilled inthe art and are described, for example, in Ullmanns Enzyklopädie dertechnischen Chemie, Vol. 1, 3rd Edition, 1951, p. 769 ff. In general,the process of the present invention is carried out using an autoclavewhich may, if desired, be provided with a stirrer and an internallining.

The composition of the synthesis gas comprising carbon monoxide andhydrogen used in the process of the present invention can vary within awide range. The molar ratio of carbon monoxide to hydrogen is generallyfrom about 5:95 to 70:30, preferably from about 40:60 to 60:40.Particular preference is given to using a molar ratio of carbon monoxideto hydrogen in the region of about 1:1.

The temperature in the hydroformylation reaction is generally in a rangefrom about 20 to 180° C., preferably from about 50 to 150° C. Thereaction is generally carried out at the partial pressure of thereaction gas at the reaction temperature chosen. The pressure isgenerally in a range from about 1 to 700 bar, preferably from 1 to 600bar, in particular from 1 to 300 bar. The reaction pressure can bevaried as a function of the activity of the hydroformylation catalystused. In general, the catalysts based on phosphorus-, arsenic- orantimony-containing compounds which are used according to the presentinvention allow reaction in a low pressure range, for example in therange from 1 to 100 bar.

The hydroformylation catalysts of the present invention and those usedaccording to the present invention can be separated from the output fromthe hydroformylation reaction by customary methods known to thoseskilled in the art and can generally be reused for the hydroformylation.

The above-described novel catalysts which comprise chiral compounds ofthe formula I are suitable for enantioselective hydroformylation.

The above-described catalysts can also be immobilized on a suitablesupport, e.g. made of glass, silica gel, synthetic resins, etc., in asuitable manner, e.g. by binding via functional groups suitable asanchor groups, adsorption, grafting, etc. They are then also suitablefor use as solid-phase catalysts.

Surprisingly, the hydroformylation activity of catalysts based onphosphine ligands of the formula I is generally higher than the activityin respect of isomerization to form internal double bonds. The catalystsof the present invention and those used according to the presentinvention advantageously display a high selectivity to α-aldehydes orα-alcohols in the hydroformylation of α-olefins. In addition, thehydroformylation of internal linear olefins (isomerizinghydroformylation) generally also gives good yields of α-aldehydes or-alcohols and in particular n-aldehydes or -alcohols. Furthermore, thesecatalysts generally have a high stability under hydroformylationconditions, so that they generally make it possible to achieve longercatalyst operating lives than are achieved using the catalysts based onconventional chilating ligands known from the prior art. Furthermore,the catalysts of the present invention and those used according to thepresent invention advantageously display a high activity, so that thecorresponding aldehydes or alcohols are generally obtained in goodyields. In the hydroformylation of α-olefins and also of internal,linear olefins, they also display a very low selectivity to thehydrogenation product of the olefin used.

The invention further provides for the use of catalysts comprising atleast one complex of a metal of transition group VIII with at least onecompound of the formula I, as described above, for hydroformylation,carbonylation and hydrogenation.

The invention is illustrated by the nonrestrictive examples below.

EXAMPLES

The following ligands were used for hydroformylation:

I. Preparation of the LigandsI.1 Preparation of Ligand DPreparation of 2,2′-dihydroxy-3,3′-di-tert-butyl-5,5′-dimethoxy-1,1′-biphenyl

In a 1000 ml flask fitted with dropping funnel and large egg-shapedstirrer, 10 g of 3-tert-butyl-4-hydroxyanisole are dissolved in 300 mlof methanol. Over the course of one hour, a solution of 1.07 g of KOHand 18.3 g of K₃(Fe(CN)₆) in 300 ml of water is added dropwise. As thepoint of introduction, the solution becomes blue and the mixtureacquires a pink mother-of-pearl color with salt precipitation. Themixture is stirred for another two hours at room temperature. 200 ml ofwater are then added, resulting in partial dissolution of the whiteprecipitate. The suspension is transferred to a 2 l separating funneland extracted twice with 500 ml each time of ethyl acetate. The aqueoussolution is extracted once with 150 ml of ether and the combined organicphases are washed with 200 ml of saturated NaCl solution and dried overNa₂SO₄. Removal of the solvent on a rotary evaporator gives 9.8 g of alight-brown solid. Washing the crude product with n-hexane gives a whitepowder. The yield based on the light-brown powder was 100% of theory.

Preparation ofdibenzo[d,f]-2,2′-di-tert-butyl-4,4′-dimethoxy-[1,3,2]-dioxyphosphochloride

The 2,2′-dihydroxy-3,3′-di-tert-butyl-5,5′-dimethoxy-1,1′-biphenyl wasfreed of oxidation products by washing with small amounts of ethylacetate. 10 g (27.9 mmol) of the biphenyl were placed in a 500 ml flaskfitted with a condenser and dried azeotropically three times using 10 mlof toluene each time and subsequently dissolved in 110 ml of toluene. Acatalytic amount (0.24 g) of N-methylpyrrolidone (NMP) was subsequentlyadded. One equivalent of PCl₃ (6.29 g) was added via a septum. Thesolution was heated at 95° C. for 24 hours, with a constant stream ofargon gas being passed through the apparatus to remove the HClliberated. Via a T-piece at the top of the condenser, the HCl-containingstream of argon was passed into an alcoholic KOH solution. After thereaction was complete, the toluene and any traces of PCl₃ present weretaken off, giving a brown oil. After addition of 10 ml of fresh toluene,the product was dried by means of a high vacuum pump, giving a dry brownpowder. The phosphonite obtained was stored under argon in a Schlenktube at −20° C. The yield of the light-brown powder was 100% of theory.

Preparation of Ligand D

This was prepared by reacting 9,9-dimethylxanthene withdibenzo[d,f]-2,2′-di-tert-butyl-4,4′-dimethoxy-[1,3,2]-dioxaphosphochloride.

II. Hydroformylations

Example 1

Hydroformylation of 1-octene Using Ligand A

0.79 mg of dicarbonylrhodium acetylacetonate and 16.5 mg of ligand A (60ppm of Rh, ligand/metal ratio=6.1:1) were weighed out separately, eachdissolved in 1.3 g of toluene, mixed and treated at 100° C. with asynthesis gas mixture of CO/H₂ (1:1) at 10 bar in a 300 ml steelautoclave provided with a sparging stirrer. After 30 minutes, theautoclave was depressurized, 2.6 g of 1-octene were then added and themixture was hydroformylated at 100° C. and 10 bar for another 4 hours.The conversion was 98%, the aldehyde selectivity was 48% and thelinearity was 81%. The proportion of a-isomers (n-aldehyde andisoaldehyde) was 96%.

Example 2

Hydroformylation of 2-butene Using Ligand A

3 mg of dicarbonylrhodium acetylacetonate and 63.4 mg of ligand A (60ppm of Rh, ligand/metal ratio=6.2:1) were weighed out separately, eachdissolved in 5 g of toluene, mixed and treated at 100° C. with asynthesis gas mixture of CO/H₂ (1:1) at 10 bar in a 300 ml steelautoclave provided with a sparging stirrer. After 30 minutes, theautoclave was cooled and depressurized, 10 g of 2-butene were theninjected and a pressure of 5 bar of CO/H₂ (1:1) was set at ambienttemperature. The autoclave was subsequently heated to 140° C. andhydroformylation was carried out for 4 hours. During the reaction,further synthesis gas was introduced to maintain a constant pressure.After the reaction was complete, the autoclave was depressurized, withthe gas released being passed through a cold trap and the products fromthe reactor and the cold trap being analyzed by means of gaschromatography. The aldehyde selectivity was 93% and the linearity was69%.

Example 3

Hydroformylation of 1-octene Using Ligand B

The procedure of Example 1 was repeated using 0.79 mg ofdicarbonylrhodium acetylacetonate and 16.6 mg of ligand B (60 ppm of Rh,ligand/metal ratio=5:1), each in 1.3 g of toluene, and 2.6 g of 1-octenefor the hydroformylation. The conversion was 99%, the aldehydeselectivity was 91% and the linearity was 88%. The proportion of aproduct was 98%.

Example 4

Hydroformylation of 1-octene Using Ligand B

The procedure of Example 1 was repeated using 0.79 mg ofdicarbonylrhodium acetylacetonate and 16.6 mg of ligand B (60 ppm of Rh,ligand/metal ratio=5:1), each in 1.3 g of toluene, and 2.6 g of 1-octenefor the hydroformylation. The temperature during the hydroformylationwas 80° C. The conversion was 97%, the aldehyde selectivity was 90% andthe linearity was 90%. The proportion of a product was 100%.

Example 5

Hydroformylation of 2-butene Using Ligand B

The procedure of Example 2 was repeated using 3 mg of dicarbonylrhodiumacetylacetonate and 126 mg of ligand B (60 ppm of Rh, ligand/metalratio=9.9:1), each in 5 g of toluene, and 10 g of 2-butene for thehydroformylation. The conversion was 66%, the aldehyde selectivity was94% and the linearity was 66%.

Example 6

Hydroformylation of 1-octene Using Ligand C

The procedure of Example 1 was repeated using 0.93 mg ofdicarbonylrhodium acetylacetonate and 19.6 mg of ligand C (60 ppm of Rh,ligand/metal ratio=5:1), each in 1.55 g of xylene, and 3.1 g of 1-octenewere used for the hydroformylation. The temperature during thehydroformylation was 90° C. The conversion was 89% and the linearity was81%. The proportion of a products was 100%.

Example 7

Hydroformylation of 1-octene Using Ligand D

The procedure of Example 1 was repeated using 0.78 mg ofdicarbonylrhodium acetylacetonate and 14.9 mg of ligand D (60 ppm of Rh,ligand/metal ratio=5:1), each in 1.3 g of xylene, and 2.6 g of 1-octenefor the hydroformylation. The temperature during the hydroformylationwas 80° C. The conversion was 53%, the aldehyde selectivity was 30% andthe linearity was 82%. The proportion of a product was 100%.

Example 8

Hydroformylation of 1-octene Using Ligand E

The procedure of Example 1 was repeated using 0.87 mg ofdicarbonylrhodium acetylacetonate and 17.1 mg of ligand E (60 ppm of Rh,ligand/metal ratio=5:1), each in 1.45 g of xylene, and 2.9 g of 1-octenefor the hydroformylation. The temperature during the hydroformylationwas 90° C. The conversion was 49%, the aldehyde selectivity was 94% andthe linearity was 88%. The proportion of a product was 100%.

Example 9

Hydroformylation of 1-octene Using Ligand F

The procedure of Example 1 was repeated, except that ligand F was usedinstead of ligand A, the molar ratio of carbon monoxide to hydrogen was1:2, the temperature was 90° C., the pressure was 5 bar, the reactiontime was 4 hours. The conversion was 36%, the aldehyde selectivity was47% and the linearity was 96%.

Example 10

Hydroformylation of 1-octene Using Ligand F

The procedure of Example 1 was repeated, except that ligand F was usedinstead of ligand A, the molar ratio of carbon monoxide to hydrogen was1:2, the temperature was 120° C., the pressure was 10 bar, the reactiontime was 4 hours. The conversion was 92%, the aldehyde selectivity was33% and the linearity was 94%.

1. A process for the hydroformylation of compounds containing at leastone ethylenically unsaturated double bond by reaction with carbonmonoxide and hydrogen in the presence of a hydroformylation catalystcomprising at least one complex of a metal of transition group VIII withat least one ligand selected from among compounds of the general formulaI

where A¹ and A² are each, independently of one another, O, S,SiR^(a)R^(b), NR^(c) or CR⁵R⁶, where R^(a), R^(b), R^(c), R⁵ and R⁶ areeach, independently of one another, hydrogen, alkyl, cycloalkyl,heterocycloalkyl, aryl or hetaryl, Y¹ and Y² are each, independently ofone another, radicals containing at least one phosphorus, arsenic orantimony atom, where in each case at least two substituted orunsubstituted heteroatoms selected from among O, S and NR^(c), whereR^(c) is hydrogen, alkyl, cycloalkyl or aryl, are directly bound to thephosphorus, arsenic or antimony atom, and R¹, R², R³ and R⁴ are each,independently of one another, hydrogen, alkyl, cycloalkyl,heterocycloalkyl, aryl, hetaryl, COOR^(d), COO⁻M⁺, SO₃R^(d), SO⁻ ₃M⁺,NE¹E², NE¹E²E³⁺X⁻, alkylene-NE¹E²E³⁺X⁻, OR^(d), SR^(d),(CHR^(e)CH₂O)_(x)R^(d), (CH₂N(E¹))_(x)R^(d), (CH₂CH₂N(E¹))_(x)R^(d),halogen, trifluoromethyl, nitro, acyl or cyano,  where R^(d), E¹, E² andE³ are identical or different radicals selected from among hydrogen,alkyl, cycloalkyl and aryl, R^(e) is hydrogen, methyl or ethyl, M⁺ is acation, X⁻ is an anion, and x is an integer from 1 to 120, or R¹ and/orR³ together with two adjacent carbon atoms of the benzene ring to whichthey are bound form a fused ring system having 1, 2 or 3 further rings.2. A process as claimed in claim 1, wherein, in the formula I, Y¹ and Y²are each, independently of one another, a radical of the formulaP(OR⁷)(OR⁸), OP(OR⁷)R⁸ or OP(OR⁷)(OR⁸), where R⁷ and R⁸ are each,independently of one another, alkyl, cycloalkyl, heterocycloalkyl, arylor hetaryl which may bear one, two or three substituents selected fromamong alkyl, cycloalkyl, heterocycloalkyl, aryl, hetaryl, COOR^(f),COO⁻M⁺, SO₃R^(f), SO⁻ ₃M⁺, NE⁴E⁵, alkylene-NE⁴E⁵, NE⁴E⁵E⁶⁺X⁻,alkylene-NE⁴E⁵E⁶⁺X⁻, OR^(f), SR^(f), (CHR^(g)CH₂O)_(y)R^(f),(CH₂N(E⁴))_(y)R^(f), (CH₂CH₂N(E⁴))_(y)R^(f), halogen, trifluoromethyl,nitro, acyl and cyano,  where R^(f), E⁴, E⁵ and E⁶ are identical ordifferent radicals selected from among hydrogen, alkyl, cycloalkyl oraryl, R^(g) is hydrogen, methyl or ethyl, M⁺ is a cation, X⁻ is ananion, and y is an integer from 1 to 120, or R⁷ and R⁸ together with thephosphorus atom and the oxygen atom(s) to which they are bound form a 5-to 8-membered heterocycle to which one, two or three cycloalkyl,heterocycloalkyl, aryl or hetaryl groups may additionally be fused,where the heterocycle and, if present, the fused-on groups may eachbear, independently of one another, one, two, three or four substituentsselected from among alkyl, cycloalkyl, heterocycloalkyl, aryl, hetaryl,COOR^(f), COO⁻M⁺, SO₃R^(f), SO⁻ ₃M⁺, NE⁴E⁵, alkylene-NE⁴E⁵, NE⁴E⁵E⁶⁺X⁻,alkylene-NE⁴E⁵E⁶⁺X⁻, OR^(f), SR^(f), (CHR^(g)CH₂O)_(y)R^(f),(CH₂N(E⁴))_(y)R^(f), (CH₂CH₂N(E⁴))_(y)R^(f), halogen, trifluoromethyl,nitro, acyl and cyano, where R^(f), R^(g), E⁴, E⁵, E⁶, M⁺, X⁻ and y areas defined above.
 3. A process as claimed in claim 1, wherein thecompound of the formula I is selected from among compounds of theformulae I.1 to I.6

A¹ is O, S or CR⁵R⁶, where R⁵ and R⁶ are each, independently of oneanother, hydrogen or C_(1-C) ₄-alkyl, R¹⁷, R¹⁸, R¹⁹, R²⁰, R²¹, R²², R²³and R²⁴ are each, independently of one another,  hydrogen, alkyl,cycloalkyl, heterocycloalkyl, aryl, hetaryl, COOR^(f), COO⁻M⁺, SO₃R^(f),SO⁻ ₃M⁺, NE⁴E⁵, alkylene-NE⁴E⁵, NE⁴E⁵E⁶⁺X⁻, alkylene-NE⁴E⁵E⁶⁺X⁻, OR_(f),SR^(f), (CHR^(g)CH₂O)_(y)R^(f), (CH₂N(E⁴))_(y)R^(f),(CH₂CH₂N(E⁴))_(y)R^(f), halogen, trifluoromethyl, nitro, acyl and cyano, where R^(f), E⁴, E⁵ and E⁶ are identical or different radicals selectedfrom among hydrogen, alkyl, cycloalkyl and aryl, R^(g) is hydrogen,methyl or ethyl, M⁺ is a cation, X⁻ is an anion, and y is an integerfrom 1 to
 120. 4. A process as claimed in claim 2, wherein the metal oftransition group VIII is selected from among cobalt, ruthenium, iridium,rhodium, palladium and platinum.
 5. A process as claimed in claim 3,wherein the catalyst further comprises at least one additional ligandselected from among halides, amines, carboxylates, acetylacetonate,arylsulfonates and alkylsulfonates, hydride, CO, olefins, dienes,cycloolefins, nitriles, N-containing heterocycles, aromatics andheteroaromatics, ethers, PF₃, phospholes, phosphabenzenes andmonodentate, bidentate and polydentate phosphine, phosphinite,phosphonite, phosphoramidite and phosphite ligands.
 6. A process asclaimed in claim 4, wherein the unsaturated compound used for thehydroformylation is selected from among internal linear olefins andolefin mixtures in which at least one internal linear olefin is present.